Can you share how your tools are setup in RRF and also have a loog at the gcode generated by the slicer and see what it is actually sending to change tools.

It could be that RRF defaults to Tool 0, Tool 1 etc while it looks like you might be using Tool 1, Tool 2 etc. Although i thought slic3r had something built in to translate between the two numbering schemes.

slic3r used to force you to number tools from 0. Long ago when RRF numbered tools from 1, I added a tool number translation facility to RRF. That facility is still there (M563 with S parameter only), although it's rarely if ever used now and I plan to remove it.

Slic3R is a bit cranky. It kind of refers to tools starting with number 1 (although it call them extruders rather than tools) but then it takes 1 off the extruder number when it generates the gcode file. What I mean is that when you assign extruder 1 to a part, the generated gcode will have T0. Personally I've become used to referring to my tools starting form zero and adding one to the tool number when I assign tools to parts in Slic3R. So for tool 0 select extruder1, for tool 1 select extruder 2 etc. The gcode will then show T0 and T1 correctly. It can be confusing until you get used to it.

Post your config.g - at least the part that defines tools and also let us know what you mean by "dual hot end". Are you using two nozzles, each with their own heater and extruder? Assuming two separate hot ends, the your config.g should look something like this

M563 P0 D0 H1
G10 P0 Xnnn Ynnn
M563 P1 D1 H2
G10 P1 Xnnn Ynnn

If it's a single nozzle then the heater number will be the same for both (H1 most likely) but the drive number will differ.

In Slic3R you use extruders 1 and 2 but the gcode will have commands for T0 and T1 which will correspond to the tool numbers in the above config.g. If you've defined tools P1 and P2 in your config.g (but no P0) then use extruders 2 and 3 in Slic3R which will generate gcode for Tool1 and Tool2.

Yes, I think I know what's probably happening. For the main part of the print Slic3R will select the "default" extruder (tool) and this is generally the first tool or no tool (I know, it's weird). Try selecting the object when it's on the platter (it'll be green when selected, but yellow when deselected) then go - Object (from the top where it says File Plater Object etc). You'll be presented with a new window with a tree that starts with "Object" - then the name of your main stl. Click on that, then lower down you'll see "Extruder" and next to it is a box with the word "default") and a drop down arrow. Click the arrow to select Extruder 2 (which will be tool 1). Then go back to print settings and set the perimeter extruder, infill extruder, solid infill extruder all to Extruder 2 (tool1) and support material to extruder 1 (tool0). Based on what you've said about the hot end being a chimera and the config.g you've posted, that should print the object using tool 1 and the support material using tool 0.

Yes, I think I know what's probably happening. For the main part of the print Slic3R will select the "default" extruder (tool) and this is generally the first tool or no tool (I know, it's weird). Try selecting the object when it's on the platter (it'll be green when selected, but yellow when deselected) then go - Object (from the top where it says File Plater Object etc). You'll be presented with a new window with a tree that starts with "Object" - then the name of your main stl. Click on that, then lower down you'll see "Extruder" and next to it is a box with the word "default") and a drop down arrow. Click the arrow to select Extruder 2 (which will be tool 1). Then go back to print settings and set the perimeter extruder, infill extruder, solid infill extruder all to Extruder 2 (tool1) and support material to extruder 1 (tool0). Based on what you've said about the hot end being a chimera and the config.g you've posted, that should print the object using tool 1 and the support material using tool 0.

Hmmm, having looked at your first screen shot, I'm a bit confused too.

On my versions of Slic3R (all of them), at the top, I have from left to right File, Plater, Object, Window, View, and Help. Under that I have Plater, Print Settings, Filament Settings, and Printer Settings. I'm not seeing those same items on your screen shot. Maybe you have installed some sort of cut down version of Slic3R ?

Anyway, without a plater tab, how are you managing to add an object to the plater? However you have managed to achieve that, can you then right click on it to bring up a menu?